These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Contrasting impacts of pre- and post-application aging of biochar on the immobilization of Cd in contaminated soils.
    Author: Xu Z, Xu X, Tsang DCW, Cao X.
    Journal: Environ Pollut; 2018 Nov; 242(Pt B):1362-1370. PubMed ID: 30138828.
    Abstract:
    Biochar has been used for immobilizing heavy metals in soils due to its abundant surface functional groups and mineral components. However, as carbonaceous material, biochar in soils is susceptible to natural aging, which could alter its structural properties and ability to retain heavy metals. In this study, the impacts of pre- and post-application aging on the properties of dairy manure and sawdust biochars and the significance of different mechanisms of complexation with surface functional groups and mineral precipitation for Cd immobilization in soils were investigated. The simulated natural aging including 25 dry-wet cycles and 25 freeze-thaw cycles decreased the pH of biochar from 8.2 to 10.7 to 7.5-9.7 while increased the release of dissolved organic carbon from 4.1 to 10.9 to 5.9-21.3 mg L-1, O/C ratios from 0.09 to 0.30 to 0.17-0.33, and O-containing functional groups, especially -OH and -C=O groups. New minerals such as CaC2O4 and MgO·MgCO3 were formed during freeze-thaw cycles. The capacity of pre-aged biochars to immobilize Cd in soils decreased from 57-70% to 53-63%, compared to that of fresh biochar, which was mainly due to decrease of CdCO3 or Cd3(PO4)2 precipitation as evidenced by XRD and MINTEQ modeling. By contrast, post-aging of biochar application in soil with dry-wet and freeze-thaw cycling had little effect on the biochar's alkalinity while increased the O/C ratios from 0.10 to 0.24 to 0.15-0.27 and intensity of O-containing functional groups. The immobilization capacity of biochars for Cd in soil increased from 44-68% to 59-73% due to the enhanced surface complexation with O-containing groups. In short, biochar subjected to pre-aging had a reduced capacity to immobilize Cd, while biochars with post-aging in soil increased its Cd immobilization capacity as a soil amendment.
    [Abstract] [Full Text] [Related] [New Search]